Ebola outbreak detection and response since 2013
Authors: Lee M Hampton, Francisco Luquero, Alejandro Costa, Anais Legand, Pierre Formenty
Journal: The Lancet Microbe (2023)

The 2022 Sudan virus disease (SVD) outbreak in Uganda is the latest reported outbreak caused by an Ebola virus species, and highlights the importance of the continued development and deployment of new tools (diagnostic tests, vaccines, and therapeutics) as part of a multifaceted approach to controlling such outbreaks. Since the start of the 2013–16 west Africa Ebola virus disease (EVD) outbreak, 12 outbreaks caused by an Ebola virus have been reported (appendix).1WHODisease outbreak news.https://www.who.int/emergencies/disease-outbreak-newsDate accessed: April 18, 2023Google Scholar, 2Centers for Disease Control and PreventionHistory of Ebola virus disease (EVD) outbreaks.https://www.cdc.gov/vhf/ebola/history/chronology.htmlDate accessed: April 18, 2023Google Scholar, 3WHO African Regional OfficeOutbreaks and emergencies bulletin.https://www.afro.who.int/health-topics/disease-outbreaks/outbreaks-and-other-emergencies-updatesDate accessed: April 18, 2023Google Scholar, 4Baize S Pannetier D Oestereich L et al.Emergence of Zaire Ebola virus disease in Guinea.N Engl J Med. 2014; 371: 1418-1425Crossref PubMed Scopus (1051) Google Scholar, 5Maganga GD Kapetshi J Berthet N et al.Ebola virus disease in the Democratic Republic of Congo.N Engl J Med. 2014; 371: 2083-2091Crossref PubMed Scopus (177) Google Scholar, 6Kiggundu T Ario AR Kadobera D et al.Notes from the field: outbreak of Ebola virus disease caused by Sudan ebolavirus: Uganda, August–October 2022.MMWR Morb Mortal Wkly Rep. 2022; 71: 1457-1459Crossref PubMed Google Scholar The interval from the onset of symptoms in the case index to confirmation of the outbreak exceeded 33 days in only three outbreaks: the west Africa EVD outbreak, the 2018–20 EVD outbreak in north Kivu province of the Democratic Republic of the Congo, and the 2022 Uganda SVD outbreak. These outbreaks are also the only ones exceeding 150 reported cases, and the first two at least were very expensive, costing international donors alone a minimum of $1·8 billion and $730 million, respectively.7Quirk EJ Gheorghe A Hauck K A systematic examination of international funding flows for Ebola virus and Zika virus outbreaks 2014-2019: donors, recipients and funding purposes.BMJ Glob Health. 2021; 6e003923Crossref PubMed Scopus (2) Google Scholar Vaccines to prevent EVD are available and WHO prequalified, and have been deployed in nine outbreaks,8WHOPrequalified vaccines.https://extranet.who.int/pqweb/vaccines/prequalified-vaccinesDate accessed: April 18, 2023Google Scholar with the number of individuals vaccinated ranging from 550 to 345 000. Collectively, these 12 outbreaks have shown that along with rapid outbreak detection, early containment of Ebola virus outbreaks depends on successful and rapid identification, isolation, and treatment of cases, contact tracing, implementation of appropriate infection prevention-and-control measures in health facilities, safe and dignified burials, engagement with affected communities,9Bedson J Jalloh MF Pedi D et al.Community engagement in outbreak response: lessons from the 2014–2016 Ebola outbreak in Sierra Leone.BMJ Glob Health. 2020; 5e002145Crossref Scopus (20) Google Scholar and, when possible, timely use of vaccines. All of these elements are crucial for ending an Ebola virus outbreak. The potential benefit of new tools for Ebola virus outbreak control is illustrated by the capabilities brought by validated commercial molecular diagnostic tests. Along with the will of countries to improve their testing capacity and international support, such tests have enabled 23 African countries to have Ebola virus diagnostic capacity, compared to five in 2010. Open-platform PCR test kits have regularly allowed confirmation of Ebola virus outbreaks within a day or less of samples from suspected cases arriving at diagnostic laboratories and confirmation of cases throughout outbreaks, whereas closed-platform cartridge-based nucleic-acid amplification tests have provided valuable surge capacity during confirmed EVD outbreaks. When combined with timely identification, reporting, and investigation of suspected cases through health facility-based surveillance, reliable sample collection and transportation, capable staff and adequate facilities at the laboratories using them, external quality-assurance testing and technical assistance to verify the reliability of laboratories, and capacity and political will to act on the results, Ebola virus molecular tests can allow rapid triggering of outbreak responses. Such surveillance and testing capacity has also greatly aided the subsequent management of outbreaks. For example, molecular testing allows identification of Ebola virus species and deployment of vaccines matching the species; and, when combined with surveillance data on cases and contacts, implementation of ring vaccination and other targeted immunisation strategies. Two vaccines are prequalified by WHO (Merck VSV-ZEBOV and Jansen Ad26.ZEBOV/MVA-BN-Filo) for protecting people against EVD.8WHOPrequalified vaccines.https://extranet.who.int/pqweb/vaccines/prequalified-vaccinesDate accessed: April 18, 2023Google Scholar An EVD vaccine stockpile, composed of Merck VSV-ZEBOV that confers rapid protection after one dose, is now accessible to all countries through the International Coordinating Group on Vaccine Provision.10WHOICG for Ebola virus disease vaccine.https://www.who.int/groups/icg/ebola-virus-diseaseDate accessed: April 18, 2023Google Scholar EVD vaccine use has focused on contacts of cases and contacts of contacts as well as front-line workers in outbreak-affected areas. However, EVD vaccine-deployment strategies might continue to evolve, particularly given emerging data on the duration of protection of EVD vaccines and the potential for Ebola virus outbreaks to originate from human and zoonotic reservoirs. For example, full-genome sequencing results have indicated that four EVD outbreaks in the Democratic Republic of the Congo and Guinea were linked to viral persistence in EVD survivors.1WHODisease outbreak news.https://www.who.int/emergencies/disease-outbreak-newsDate accessed: April 18, 2023Google Scholar, 2Centers for Disease Control and PreventionHistory of Ebola virus disease (EVD) outbreaks.https://www.cdc.gov/vhf/ebola/history/chronology.htmlDate accessed: April 18, 2023Google Scholar, 3WHO African Regional OfficeOutbreaks and emergencies bulletin.https://www.afro.who.int/health-topics/disease-outbreaks/outbreaks-and-other-emergencies-updatesDate accessed: April 18, 2023Google Scholar Development of new EVD vaccination strategies, including preventive vaccination outside of outbreaks, requires further evidence on a range of issues, including the feasibility, acceptability, cost-effectiveness, and affordability of each strategy, the duration of protection, and the benefit of vaccinating EVD survivors and their contacts. Such factors, along with the safety, effectiveness, and time to protection of potential SVD vaccines, will also need to be considered for development of possible SVD-vaccination strategies. As the world looks to better prepare for future epidemics, the experience with Ebola virus outbreaks illustrates the importance of strong country capacity and long-term commitment to detect and respond to outbreaks. It also shows how sustained international efforts can constructively support such country efforts. Perhaps most importantly, the Ebola virus experience demonstrates the value of a multifaceted approach to disease control that integrates diagnostic testing and surveillance, vaccination, adequate case management, non-pharmaceutical interventions including community engagement and social mobilization activities, continuous monitoring and learning, and other measures for the detection and control of epidemic-prone diseases. Download .pdf (.19 MB) Help with pdf files Supplementary appendix